Archaeologists Discover Mysterious Stone Circle Built Before Great Pyramids

Archaeologists have discovered a mysterious stone circle in the Andes Mountains that they say was constructed before the great pyramids of Egypt.

The circular stone plaza, which measures around 60 feet in diameter, consists of two concentric walls made from unshaped stones set vertically in the ground, according to a study reporting the find in the journal Science Advances.

The monument is located in northern Peru's Cajamarca Valley at the Callacpuma archaeological site, which lies around 10,000 feet above sea level near the summit of a peak in the Andes. Stretching for more than 5,000 miles along the western edge of South America, the Andes range is the longest in the world.

Using radiocarbon dating techniques, researchers determined that initial construction of the circular plaza took place around 4,750 years ago, corresponding to the "Late Precaremic" period of Andean archaeology.

"This structure was built approximately 100 years before the great pyramids of Egypt and around the same time as Stonehenge," Jason Toohey, anthropological archaeologist with the University of Wyoming and lead author of the study, said in a press release.

The circular plaza is an example of monumental megalithic architecture, which refers to prehistoric structures built using large stones. According to the study, the find at Callacpuma represents one of the earliest examples of monumental, megalithic ceremonial architecture in the Americas.

"This plaza is significant because it is a very early example of public, monumental, and megalithic architecture. There are a few slightly earlier examples in the Andes—and many more recent—but this is the earliest and only example like this from the Cajamarca region of northern Peru," Toohey told Newsweek.

The monument was built using large, free-standing and vertically placed megalithic stones. This construction method has never been reported before in the Andes and is distinct from other monumental plazas in the region, the researchers said.

The people living in the Cajamarca Valley during this period were at a "really interesting" place in terms of economy and social organization, according to Toohey.

"These were relatively small groups of people, who were still relatively mobile, probably still hunting and gathering to some extent. But this is also the time when people were beginning to experiment with food production—horticulture and perhaps some animal husbandry. This is just that time when people were just beginning to settle down and produce their own food," he said.

Little is known about why exactly the plaza was constructed, but the form and scale of the monument—as well as the lack of domestic artifacts in the vicinity—indicate that it was probably ceremonial in function.

According to Toohey, the plaza probably served as a gathering place and ceremonial location for some of the earliest people living in this part of the Cajamarca Valley.

"The question of its purpose is a huge one. I am very interested in why people from a small-scale relatively mobile society would go to the trouble and labor to construct such a monument—and this certainly is by no means the only example of these early monumental plazas in the Andes or elsewhere in the world," the researcher told Newsweek.

"I suspect—and I am not the first archaeologist to propose this kind of idea—that people from one group or members of several nearby groups either came together under the leadership of some aspiring person, or, and just as likely, that they came together more collectively in order to build this monument. We may never know exactly what happened and why the monument was built, But at a time when people were just beginning to settle down, there might have been some desire to make a physical, material claim to local resources and lands," he said.

Monumental architecture is associated with social complexity in ancient human societies, yet the drivers of its origins remain poorly understood.

"This form of architecture is purposefully constructed to be larger and sometimes more elaborate than is needed given its intended function," the authors wrote in the study.

The world's earliest ceremonial monumental architecture—whether represented by alignments of megalithic stones, large platforms and buildings, or bounded plazas—tended to be the result of communal action by groups larger than immediate households, and often larger than the population of the local area.

Early well-known examples of ceremonial architecture of this kind include the renowned site of Göbekli Tepe in Turkey, Stonehenge in England and the great pyramids of Giza in Egypt.

Göbekli Tepe—thought to have been constructed by around 9000 B.C.—is "particularly important" here because it was constructed during the pre-pottery Neolithic period (otherwise known as the New Stone Age) by hunting-gathering-foraging peoples on the cusp of sedentary life and food production, the authors said in the study.

"As with the case of early monumental collective architecture outside Andean South America, for instance at Göbekli Tepe, the construction of monumental ritual architecture in the Late Preceramic of the coastal and highland central Andes represented a shifting social world perhaps involving a change from small group-related belief systems to more collective and regionally focused belief and action," the study authors wrote.

The next steps for the researchers at the Callacpuma Plaza will be to investigate the area with non-invasive remote sensing technologies in order to look for buried walls and other features that may be associated with the monument. The results of this analysis will guide the team in future excavations at the site.

"We have no other archaeological sites of this time period in the Cajamarca Valley—and it would be great to find other associated remains," Toohey said. "I suspect that when people came for periodic events at the plaza, they lived very nearby for perhaps several days at a time."

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Update 03/01/24, 3:12 p.m. ET: This article has been updated to include additional comments from Jason Toohey.